USL JSD-60 Manual - Manual (Page 41)

Page 41
11. Adjust the Bass and Treble controls to provide the required low and high frequency response.
12. Adjust the remaining equalizer controls to put each RTA band within the limit lines. Avoid extreme variation
between adjacent equalizer values. The auditorium will generally sound best applying the least equalization
possible while remaining within the curve limit lines.
13. Adjust the Equalizer Tab gain control for the desired auditorium SPL.
14. Turn off the generator.
15. Use the copy button to copy the equalization to each of the other channels as a starting point.
16. Go back to step 6 to equalize the next channel.
8.11.5 LFE Equalization Procedure
The LFE channel uses a parametric equalizer instead of a graphic equalizer. In the below image, the leftmost Gain
control is the master LFE gain that applies to all LFE outputs. It corresponds to the LFE gain control shown on the
Outputs tab. Within each LFE box is another gain control that applies to ONLY that LFE output. The box also
contains the parametric filter controls (PEQ gain, Q, and frequency) that applies to that particular LFE output.
The GUI determines the capabilities of the particular JSD-60 hardware and only shows the appropriate number of
LFE outputs.
A suggested LFE adjustment procedure is below. Note that selecting the LFE channel in the equalizer tab does NOT
turn off pink noise on the previously selected channel. This is different than the behavior on all other channels.
This difference allows pink noise to drive the LFE and center channels simultaneously so the transition frequency
region can be viewed for possible phase errors. When the LFE channel is selected on the equalizer tab, a warning
box (shown in the image below) will appear if pink noise is currently driving another channel. The procedure below
drives the LFE and center channels simultaneously.
1. On the Equalizer tab, select the Center channel, Pink noise, and turn on the generator. Pink noise should be
visible on the RTA based on the equalization done in the previous section.
2. Select the LFE channel. The warning box should appear indicating that the center channel is also being driven.
At this point, pink noise is driving both the center and LFE channels.
3. Adjust the leftmost (master) gain control until the LFE level matches the mid-band level of the center channel
on the RTA display.
4. Adjust the frequency control to the worst dip or peak in the LFE portion of the RTA display.
5. Set the Q to 4 and adjust the PEQ gain as required to remove the peak or dip. The Q can be increased to make
the peak or notch narrower, or decreased to make it wider. The frequency can be adjusted as required to
center the peak or notch on the notch or peak displayed on the RTA.
6. If desired, a higher pass filter can be enabled under the filters tab adjusted to add a bit more low frequency
range. Try increasing the Q above the default 0.707, then adjust the frequency as required to yield a flatter LFE
response. A Q above 0.707 adds a peak at the filter cutoff frequency before the rolloff begins.
7. If there is a notch in the transition region between the LFE and center channel frequencies, try reversing the
phase on the LFE channel (Invert button on the Stage Out tab).
8. Finally, adjust the leftmost gain control up to increase the LFE output as required. SMPTE RP 200-2002 calls for
LFE to be 10dB above the center channel, but this may be excessive in some auditoriums.
9. If the JSD-60 has multiple LFE outputs, the individual PEQ controls can be adjusted similarly.